This research note presents evidence on the conditions that influence governments? decisions to commit themselves to international human rights regimes. Are governments pressured by powerful state actors to make such commitments, as some realists have suggested? Or rather do governments to cede the right to review internal rights policies to external authorities as the result of socialization through persuasion? What role do domestic political conditions and institutions play? This research note offers empirical evidence that addresses these issues. Using global data relating to the six "core" UN human rights treaties, I find the strongest evidence of external socialization, although governments presiding over common law legal systems tend to resist formalizing their rights commitments in external treaty form. There is little evidence of democratic "lock–in" using these data, although this remains a persuasive interpretation of the origins of the European human rights regime.